How can i rotate root axis when using ART in maya?

Hey guys, i’ve leart how to use ART in maya and tried to make some change to the default animation of the default character of UE4, but when i import that animation into UE4, i found that the root axis of my animation was wrong. It has taken me several hours to rotate it back to correct axis but i couldn’t find any way useful yet, if u knows how to fix it ,pls help~